菜豆根瘤菌对土壤无机磷的活化释放作用  

EFFECT OF RHIZOBIUM PHASEOLI ON MOBILIZATION AND RELEASE OF INORGANIC PHOSPHORUS IN SOIL

作　　者：张亮[1] 黄建国[1] 

机构地区：[1]西南大学资源环境学院,重庆400716

出　　处：《土壤学报》2012年第5期996-1002,共7页Acta Pedologica Sinica

基　　金：中央高校基本科研业务费专项XDJK(2010D002)资助

摘　　要：以土壤为磷源,通过液体培养研究了7株菜豆根瘤菌(Rhizobium sp.)对土壤磷的利用。结果表明,菜豆根瘤菌能释放大量的氢离子,使液体培养基的pH大幅度降低,氢离子的浓度至少提高20倍以上。根瘤菌分泌有机酸的种类与数量因菌株不同而异,这些有机酸包括甲酸、乙酸、草酸、丁二酸、柠檬酸、苹果酸和乳酸等,大部分根瘤菌能分泌乙酸。在接种根瘤菌的液体培养基中,全磷含量显著高于不接种的液体培养基,土壤无机磷总量则显著降低。由于土壤是培养基磷的唯一来源,故根瘤菌可促进土壤无机磷的溶解释放。相关分析表明,培养基的pH与土壤无机磷总量呈极显著正相关(r=0.893**,n=8),说明根瘤菌分泌的氢离子可能是溶解土壤无机磷的原因之一。接种根瘤菌显著降低土壤闭蓄态磷,土壤中的铁磷、铝磷和钙磷因菌株不同而降低,其原因可能与有机酸分泌的数量和种类有关。根瘤菌既能释放氢离子又可分泌多种有机酸的现象表明其活化土壤无机磷的方式具有多样性,可能有益于豆科植物利用不同形态的难溶性磷,使之适应各种不同的低磷土壤。Seven strains of Rhizobium sp. were cultured in liquid mediums using soil as the sole source for phosphor- us to investigate effect of the strains on mobilization and release of phosphorus in soil. The control treatment was set in the same way except inoculation of Rhizobia. Results suggest that the bacteria released a large amount of hydrogen ions, thus making the concentration of the ions multiplied by at least 20 times, which resulted in a significant decrease in pH of the solution. Different strains of Rhizobia released different types and amounts of organic acids, including oxalic acid, malic acid, succinic acid, formic acid, acetic acid, citric acid and lactic acid. However, most of the strains exuded acetic acid. The treatments were significantly higher than the control in total phosphorus in the liquid culture mediums, while the total inorganic phosphorus in the soil immersed in the liquid behaved otherwise. Taking into account the soil being the sole phosphorus source, it could be concluded that Rhizobia could promote mobilization and release of inorganic phosphorus from the soil. Correlation analysis shows that total phosphorous was extremely positively related to pH of the liquid （ r = 0. 893＊＊ , n = 8） , suggesting that the secretion of hydrogen ions from the bacteria is one of the causes for dissolution of in- organic phosphorus in soil. Inoculation of Rhizobia reduced occluded phosphorus in the soil remarkably, and also AI-P, Fe-P and Ca-P but to an extent varying with the stains of Rhizobia, which might be attributed to the different amounts and types of organic acids they could secret. The phenomenon of Rhizobia releasing hydrogen ions and a variety of organic acids suggests that inorganic phosphorus in the soil is mobilized in a number of ways, which demonstrates that inoculation of Rhizobia may help legume crops make use of various forms of unavailable phosphorus in the soil, thus making them adap- ted to different soils low in phosphorus.

关 键 词：菜豆根瘤菌 土壤 磷 

分 类 号：S154.3[农业科学—土壤学]